Background: Mood and anxiety disorders, and problems with self-harm are significant and serious issues that are common in young people in the Criminal Justice System. Aims: To examine whether interventions relevant to young offenders with mood or anxiety disorders, or problems with self-harm are effective. Method: Systematic review and meta-analysis of data from randomized controlled trials relevant to young offenders experiencing these problems. Results: An exhaustive search of the worldwide literature (published and unpublished) yielded 10 studies suitable for inclusion in this review. Meta-analysis of data from three studies (with a total population of 171 individuals) revealed that group-based Cognitive Behaviour Therapy (CBT) may help to reduce symptoms of depression in young offenders. Conclusions: These preliminary findings suggest that group-based CBT may be useful for young offenders with such mental health problems, but larger high quality RCTs are now needed to bolster the evidence-base. (Contains 4 tables and 3 figures.)